One or more aspects of the inventive concepts relate to a pixel for a depth sensor.
A depth sensor is a device that measures the distance between the depth sensor and a target object by measuring a delay time incurred for pulse light projected from the light source to be reflected from the target object and then to return back to the depth sensor. A pixel for the depth sensor includes a plurality of photoelectric conversion devices. Each of the photoelectric conversion devices may generate photoelectric charges according to the amount of the pulse light reflected from the light source and returning back to the depth sensor. Using the received photoelectric charges, the distance between the depth sensor and the target object may be measured by calculating the difference between a point of time when the pulse light is projected and a point of time when the pulse light is sensed is referred to as a Time of Flight (ToF). In other words, the depth sensor may calculate the distance between the depth sensor and the target object by using photoelectric charges generated by the plurality of photoelectric conversion devices in response to the received reflected light source. Further, a three-dimensional (3D) image may be formed by using color information obtained from another type of sensor.
Conventionally, each of the pixels included in a depth sensor has an independently constructed floating diffusion node or a drain node. Further, if each pixel has a drain node, then the distance between pixels may increase resulting in both a decrease in a sensitivity of the depth sensor because of a reduction in a number of sensors and a decrease in the speed of transmitting the photoelectric charges within the sensors. Therefore, the distance between the depth sensor and a target object may be incorrectly calculated. Accordingly, the distances between the photoelectric conversion devices should be reduced resulting in a reduction space requirements and improvements in the sensitivity of the depth sensor and the precision of distance calculation.